I use this, which uses a ridiculously little amount. I don't know how easy it is to overload plants with silica, I can't recommend a dosage. I use the amount recommended.
Always learning something new on AFN.
The 250ml bottle is $130 on Amazon
http://tinyurl.com/nw9azdw
That is about $2000 per gallon, too expensive for me but I like learning new stuff.
Looks like Aptus FASiLITOR is using boric and silicic acid and PEG 400 in a lower pH, lower concentration for easier absorption. Convenient for hydroponics, but not sure I want PEG 400 (Polyethylene glycol) in my buds.
Is Aptus FASiLITOR really just Silliforce.... re-branded, repackaged, re-marketed, and with a massive price increase:
http://agro-solutions.us/solutions/siliforce/
I have become a cynical, jaded, bitter, grumpy grower when it comes to nutes and might never forgive companies for encouraging overfeeding AND flushing... so greedy. I am slow and stubborn to add anything to my simple tomato plant food.
Aptus FaSilitor says their silicon is bio-available immediately.
Others silicon additives might take time for the bigger particles to break up into small pieces the plants can use.
Does it make a measurable difference for you compared to the cheaper stuff like Dyna-Gro Pro-tekt?